void writebool(bool b) {
	if (b) write(1);
	else   write(0);
}

int run() {
	int a <- 5, b <-- a;
	
	writebool(a == b);
	
	write(a);
	write(b);
	
	a <-- null;
	
	writebool(null == a !== b);
	
	write(b);
	
	b <-- null;
	
	writebool(a == b == null);
}
